1. Field of the Invention
The present invention relates to a mobile machine for felling and chipping trees.
2. Prior Art
According to the McGraw-Hill Encyclopedia of Science and Technology, Volume 7, page 651, tree-felling machines are known in which heavy-duty hydraulic-powered shears fell trees up to a stump diameter of 18 inches (45.72 cm). The shears may be mounted on or incorporated in wheeled or crawler type tractors. Such machines may both fell trees and buck them to pulpwood. The problem with such machines is that each time it is desired to fell a tree the tractor must be positioned precisely so that the tree is centered in the shears. Further, such machines do not clear land completely because no mechanism is provided for picking up slash.
U.S. Pat. No. 3,394,744 discloses a "Method and Apparatus for Felling and Treatment of Trees to Produce Wood Chips." This patent uses complicated mechanism for grasping a tree, for slicing through the tree with a rotating cutterhead and for feeding the tree downward against the cutterhead to cut the tree into chips. A problem with the method and apparatus of this patent is that the tree-grasping mechanism must be capable of supporting a severed tree upright and, consequently, only small trees may be felled and chipped by such method and apparatus.
U.S. Pat. No. 3,979,075 discloses a machine for felling and chipping "brushwood" using a pair of rotating cutterheads. One cutterhead fells trees and acts as a "reaction member" for the other cutterhead which chips the trees. However, the speed of rotation of one of the cutterheads must be constant relative to the speed of rotation of the other cutterhead. Consequently, complicated drive mechanism is required and stalling of one cutterhead effects stalling of the other cutterhead.
Other machines for shredding or chipping trees are disclosed in U.S. Pat. Nos. 3,545,692; 3,863,848; 3,955,765; and 4,057,192. These patents are concerned with processing felled trees rather than providing mechanism for felling trees.